I certainly understand the concern, but I just remind myself how involved he was with First Class and it eases my mind... a bit.

I also remember that Singer was set to go on directing First Class before WB forced him to do Jack. And considering how involved he was in First Class (I've been told he was on set nearly every day) I think he was just not that into Jack. His desire was still in the X-world.

I think he signed a multi-picture contract with WB when he did Superman.